In Germany alone, more than 20,000 traffic accidents occur every year involving people who under the influence of alcohol. Since these accidents, which are attributable to alcohol, result in death for more than 600 people and serious injury for more than 8,000 people, efforts are underway in recent years to find ways to prevent these accidents.
One of the possibilities proposed provides for using a device of the type mentioned at the outset, which is frequently also referred to as an alcohol interlock system. This device is installed in the vehicle and prevents intoxicated vehicle drivers from starting the vehicle or putting it into operation if the alcohol level of the vehicle driver exceeds a specified threshold value.
Most alcohol interlock systems in use today are based on measuring the alcohol content in the air exhaled by the vehicle driver and, for that purpose, include a measuring device for measuring the alcohol in the breath of the vehicle driver, a display device connected to the measuring device or integrated therein which indicates whether or not the measured alcohol content exceeds the specified threshold value, a control unit that communicates with the measuring device, as well as an immobilizer which, for the most part, is integrated in an ignition and starter circuit. When the vehicle driver turns on the ignition of the motor vehicle, he/she is prompted by a corresponding display on the display device to provide a breath sample to determine the alcohol content in the breath. If the alcohol content in the breath sample exceeds the specified threshold value, the power supply to the starter is blocked to prevent the motor vehicle from being driven by a driver who is under the influence of alcohol. Once a preset delay of about 10 minutes has elapsed, another breath sample can generally be given, whose alcohol content is again determined by the measuring device. The system then decides whether the vehicle should continue to be blocked by the control unit and the immobilizer or whether a start should be enabled.
However, besides measuring the alcohol in a person's breath, it is also possible, however, to measure the alcohol content in the blood, in the tissue or in the interstitial tissue fluid of the vehicle driver, for example, using infrared-based spectroscopy, or to analyze the alcohol content in the sweat of the vehicle driver's skin with the aid of chemical sensors, or to evaluate parameters that are physiologically dependent on the blood alcohol content, such as eye and head movements, as well as the heart rate of the vehicle driver, in order to ascertain a possible intoxication of the vehicle driver.
One of these options can be inferred from publications that are cited in U.S. Patent Publication No. 2003/0120139 in connection with a device for preventing start-up of a machine by an operator who is under the influence of alcohol or a different drug.
However, regardless of the technique used to determine the degree of intoxication of the vehicle driver, all of the known systems have the disadvantage that the vehicle can no longer be started for a certain minimum time period following an activation of the immobilizer, on the one hand, due to the preset delay and, on the other hand, because a certain amount of time is required for repeating the determination of the alcohol content, as is already required for the first determination of the same, for example, approximately one minute, when measuring devices are employed for measuring the alcohol content in the breath, using fuel cells at low ambient temperatures.
From Korean Patent Application No. KR 2001/011208, it is already known to activate a warning device of a vehicle when the vehicle is started or driven by an intoxicated vehicle driver. The device used for that purpose includes a sensor for ascertaining the alcohol content in the breath of the vehicle driver.
Against this background, an object of the present invention is to improve a device of the type mentioned at the outset in a way that allows the vehicle to be quickly started, at least in cases of emergency or in dangerous situations, in spite of a previously activated immobilizer.